Tags attached to ears of animals, such as dairy, beef cattle, and hogs, have been used to identify the animals. The tags have a generally flat plastic body joined to a connector adapted to be attached to the ear of an animal. Examples of this type of ear tag are shown in U.S. Pat. Nos. 3,552,051 and 3,934,368. Insect repellents and insecticides have been impregnated into the plastic of ear tags for controlling insects that are attracted to the animals. The effectiveness of the insecticide on these ear tags is of a limited duration. After a period of time, the tags are not effective to control the insects. The tags must be removed from the animal and replaced with new insecticide carrying tags. This is a costly and time-consuming procedure. If the tags are not removed, other types of insecticide control programs must be used.